1. Field of Invention
The present invention is directed to a method and an apparatus for connecting and properly orienting an attachment to a drill press. The present invention is more particularly directed to a method and an apparatus for properly aligning one or more elements of a mortising attachment during installation of the attachment on a drill press, and is further directed to a mortising apparatus including the alignment apparatus of the invention.
2. Background of Invention
The mortise-and-tenon joint is one of the strongest and most durable in all of woodworking. While the tenon typically may be cut on a table saw with relatively little difficulty, cutting the mortise is more difficult. The mortise may be carved by hand, but more typically is created using a dedicated mortising device or a specially designed mortising attachment used in conjunction with a drill press. A drill press-mounted mortising attachment eliminates the tedious handwork that otherwise would be required to cut the cavity, i.e., the mortise, which receives the tenon.
FIG. 1 illustrates certain elements of a typical drill press-mounted mortising attachment, generally identified as 10. The depicted portion of the drill press is generally identified as 12. The mortising attachment 10 includes a chisel holder 14 having an upper collar 16. The upper collar 16 is secured around the quill 18 of the drill press 12 above the chuck 20 by the clamping pressure of fastener 21. The chisel holder 14 also has two depending arms 22 which extend toward a lower collar 24, which defines a bore 26 therethrough. A mortising chisel 28 is inserted into the bore 26 of the lower collar 24 of the chisel holder 14, and is secured in place by set screw 29. A drill bit 30 designed to work in conjunction with the mortising chisel 28 may then be inserted through the central cavity of the mortising chisel 28 and up into the chuck 20, and is secured within the chuck 20. Thus, the drill bit 30 extends from the chuck 20 to the lower end 31 of the mortising chisel 28. In order to form the mortise, the chuck 20 rotates the drill bit 30 within the mortising chisel 28, and the quill 18 is lowered in order that the rotating bit 30 and the advancing mortising chisel 28 remove a generally rectangular piece of stock so as to form all or a portion of the mortise. Wood chips generated during the cutting operation by the rotating drill bit 30 are ejected from the interior of the mortising chisel 28 through a slot 32 located along a side of the mortising chisel 28.
Although not depicted in the appended figures, drill press-mounted mortising attachments typically are sold as kits that include elements in addition to a chisel holder. Such additional elements may include, for example, workpiece fences and hold-down brackets for positioning and securing the workpiece on the work support table of the drill press in a proper position for executing the one or more mortise cuts. An example of such a kit is the Delta International Machinery model 17-905 Mortising Attachment. Those of ordinary skill will be familiar with such other elements and, therefore, the elements are not depicted or described herein.
If the mortising chisel 28 and the drill bit 30 are not property aligned relative to one another when they are secured to the chisel holder 28 and the chuck 20, respectively, the wood chips may not be ejected efficiently from the mortise cut. In addition, improper alignment of the mortising chisel 28 and drill bit 30 may cause the rotating drill bit to contact the mortising chisel during cutting, resulting in vibration and/or chatter. To provide proper alignment it is typically the case that, the central axis of the drill bit 30 must be substantially coincident with the central axis of the cavity within the mortising chisel 28. Contact between the drill bit 30 and the mortising chisel 28 may cause, for example, premature wear of the parts, and the resulting vibration may result in imprecise mortise cuts.
Prior art drill press-mounted mortising attachments typically provide no feature by which to ensure proper alignment of the drill bit 30 and mortising chisel 28. The process of achieving proper alignment of these elements in the prior art mortising attachments could fairly be characterized as "hit-or-miss". That is, the mortising attachment 10 is assembled generally without regard for alignment, and if the mortising chisel 28 and the drill bit 30 are found to not be properly aligned (i.e., vibration and/or chatter results), the mortising attachment is disassembled and then reassembled as necessary to modify the orientation of the chisel holder 14 relative to the chuck 20 until proper alignment of the drill bit 30 and the mortising chisel 28 is achieved.
The hit-or-miss alignment method may be time-consuming if, for example, the drill press is needed for multiple drilling operations and the mortising bit and chisel must be installed and aligned multiple times in a given period. Moreover, even successful utilization of the hit-and-miss method of alignment naturally results in some delay and reduces the efficiency of wood shop operations. Mortise cuts executed with the mortising chisel and the drill bit misaligned may be inaccurate and, as discussed above, the cutting elements may wear prematurely.
Accordingly, there exists a need for a quick and efficient manner of properly aligning the drill bit and mortising chisel elements of a drill press-mounted mortising attachment during installation of the attachment on the drill press.